drm/colorop: add BT2020/BT709 OETF and Inverse OETF

The BT.709 and BT.2020 OETFs are the same, the only difference
being that the BT.2020 variant is defined with more precision
for 10 and 12-bit per color encodings.

Both are used as encoding functions for video content, and are
therefore defined as OETF (opto-electronic transfer function)
instead of as EOTF (electro-optical transfer function).

Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Daniel Stone <daniels@collabora.com>
Reviewed-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Sebastian Wick <sebastian.wick@redhat.com>
Signed-off-by: Simon Ser <contact@emersion.fr>
Link: https://patch.msgid.link/20251115000237.3561250-34-alex.hung@amd.com

Author: Harry Wentland

drivers/gpu/drm/drm_colorop.c

@@ -72,6 +72,8 @@ static const char * const colorop_curve_1d_type_names[] = {
 	[DRM_COLOROP_1D_CURVE_SRGB_INV_EOTF] = "sRGB Inverse EOTF",
 	[DRM_COLOROP_1D_CURVE_PQ_125_EOTF] = "PQ 125 EOTF",
 	[DRM_COLOROP_1D_CURVE_PQ_125_INV_EOTF] = "PQ 125 Inverse EOTF",
+	[DRM_COLOROP_1D_CURVE_BT2020_INV_OETF] = "BT.2020 Inverse OETF",
+	[DRM_COLOROP_1D_CURVE_BT2020_OETF] = "BT.2020 OETF",
 };
 
 /* Init Helpers */

include/drm/drm_colorop.h

@@ -82,6 +82,29 @@ enum drm_colorop_curve_1d_type {
 	 */
 	DRM_COLOROP_1D_CURVE_PQ_125_INV_EOTF,
 
+	/**
+	 * @DRM_COLOROP_1D_CURVE_BT2020_INV_OETF:
+	 *
+	 * enum string "BT.2020 Inverse OETF"
+	 *
+	 * The inverse of &DRM_COLOROP_1D_CURVE_BT2020_OETF
+	 */
+	DRM_COLOROP_1D_CURVE_BT2020_INV_OETF,
+
+	/**
+	 * @DRM_COLOROP_1D_CURVE_BT2020_OETF:
+	 *
+	 * enum string "BT.2020 OETF"
+	 *
+	 * The BT.2020/BT.709 transfer function. The BT.709 and BT.2020
+	 * transfer functions are the same, the only difference is that
+	 * BT.2020 is defined with more precision for 10 and 12-bit
+	 * encodings.
+	 *
+	 *
+	 */
+	DRM_COLOROP_1D_CURVE_BT2020_OETF,
+
 	/**
 	 * @DRM_COLOROP_1D_CURVE_COUNT:
 	 *